All laboratory studies on teratogenic potential of noise reported to date, have used the rat or mouse as the experimental animal. Yet the guinea pig is probably a more suitable experimental animal for such studies. In addition to endocrine similarity to man the audibility curve for the guinea pig is probably closer to that of the human than any other mammal except primates and chinchillas. The auditory sensitivity of rats or mice is such that the most sensitive frequency is nearly a decade above that of humans. While the guinea pig has been extensively used to investigate the effects of noise on the inner ear and on basic mechanisms of hearing the teratogenic potential of noise in the guinea pig has not been assessed.